Selective elevation of systemic blood pressure by epinephrine during sepsis-induced pulmonary hypertension in piglets

In a piglet model of group B beta Streptococci (GBS)-induced pulmonary hypertension, we have determined hemodynamic responses to epinephrine (EPI) infusion in both the systemic and pulmonary circulations. Three groups of piglets (GBS + EPI, n = 6; GBS + placebo, n = 6; placebo, n = 6) were studied. GBS, infused intravenously at approximately 5 X 10(7) organisms/kg/min, reduced cardiac index and stroke volume index while elevating pulmonary artery pressure and pulmonary vascular resistance index. Systemic vascular resistance index, heart rate and aortic pressure did not change during GBS infusion. Six piglets received intravenous EPI after cardiac index had fallen by 30% during GBS infusion. At 3.5, 7.0, and 15 micrograms/kg/min, respectively, EPI raised aortic pressure by 18.5, 31.0, and 45.0 mm Hg while EPI reduced pulmonary artery pressure by 5.2, 6.3, and 8.2 mm Hg. At each dose, EPI elevated systemic vascular resistance index and lowered pulmonary vascular resistance index. At 3.5 micrograms/kg/min, the elevation of aortic pressure was associated with an increase in both cardiac index and systemic vascular resistance index. At higher EPI doses, the rise in aortic pressure was accounted for entirely by an increase in systemic vascular resistance index. Systemic acid/base status and PaO2 did not differ among piglets who received GBS + EPI, GBS alone, or placebo. Extrapolation of these data to human infants must be approached with extreme caution. However, selective elevation of systemic blood pressure may be a feasible strategy for some infants to impede right-to-left shunting of blood often associated with sepsis-induced pulmonary hypertension.